In an OFDMA communication system, the time-frequency resources of the system are shared among a plurality of mobile stations. The base station assigns resources to mobile stations using an assignment message, which is transmitted as part of a control channel. To minimize control channel overhead, it is known for the base station to make persistent assignments, wherein the assignment message is transmitted to the mobile station initially to indicate the assigned time-frequency resource, and then the base station uses the same time-frequency resource for subsequent transmissions to (or receptions from) the mobile station.
These transmissions can be for H-ARQ transmissions of the same packet, for subsequent transmissions of different packets, or for initial transmissions of a series of packets. For example, in a voice over internet protocol (VoIP) system, the base station may make a persistent resource assignment to a particular mobile station consisting of a particular time-frequency resource with a period equal to 20 msec (the vocoder period). Then, the base station can use this resource for the first H-ARQ transmission of each VoIP packet. Subsequent transmissions, if necessary, must be signaled.
The initially assigned time-frequency resource is maintained by the base station for the mobile station until a timer elapses, a voice over internet protocol (VoIP) talk-spurt is completed, a VoIP call is completed, a certain number of negative acknowledgements is determined by the base station, or until the resource is explicitly or implicitly de-assigned by the base station.
In some systems, the base station and mobile station can maintain multiple decoding buffers corresponding to multiple ACIDs corresponding to multiple packets. For example, the base station can transmit H-ARQ transmission 1 of packet 1, followed by H-ARQ transmission 1 of packet 2, followed by H-ARQ transmission 2 of either packet 1 or packet 2. The base station and mobile station typically keep track of which packet is currently being transmitted by associating each packet with a particular ACID and including the ACID in the control channel corresponding to the packet. For persistent assignments corresponding to the transmission of multiple packets, there is not currently a method for establishing an association between the series of packets and a series of ACID values. Thus, there is a need for an efficient method for associating a series of packets signaled in a persistent assignment to a series of ACID values.